Addition Of Vanadium Research Articles

Improvement properties of laser cladding Ni45-Cr3C2 coatings by adding B4C and V

By adding B4C and vanadium to Ni45-Cr3C2 powder in a moderate proportion, it is found that B4C will decompose into elements B and C during laser cladding, and the lattice constants of V and Cr elements are similar, which can form (Cr,V)B2 phase with high hardness. According to the first principles calculation of the hardness of (CR1-XVx)B, it can be seen that it shows a trend of increasing first and then decreasing. With the addition of B4C and vanadium, the mechanical properties of the composite coating increase. When the coating composition is Ni45-30Cr3C2-9B4C-15FeV50, the average microhardness, fracture toughness and wear resistance of the composite coating increase by 22.1%, 121.6% and 54.2%, respectively. Highlights Laser cladding composite coatings with different B4C and vanadium were prepared. V and Cr elements have similar lattice constants and can form a (Cr, V)B2 phase with high hardness. The performance of the laser cladding composite coatings increased with the addition of B4C and vanadium.

Synthesis of Vanadia-Mayenite Nanocomposites and Characterization of Their Structure, Morphology and Surface Sites

Calcium aluminates (CA) with a mayenite structure have attracted a growing interest during the last decades. The present paper reports the preparation of vanadia-mayenite composites performed via an impregnation of pure CA with ammonium vanadate solution. The properties of the prepared materials were explored by a low-temperature nitrogen adsorption/desorption technique, X-ray diffraction analysis, transmission electron microscopy, and spin probe method. As revealed, the addition of vanadium significantly affects the textural properties and the porous structure of mayenite. The blockage of micropores by vanadium species is supposed. The spin probe electron paramagnetic resonance technique based on the adsorption of 1,3,5-trinitrobenzene, phenothiazine, and diphenylamine has been applied to study the active sites on the surface of the composite samples. The results demonstrated an increase in the concentration of weak electron-acceptor sites when the vanadium loading was 10 wt%. X-ray diffraction analysis and transmission electron microscopy studies showed that the composites consist of few phases including mayenite, CaO, and calcium vanadates.

The effect of vanadium addition in Ni1-xVxFe2O4 nano photocatalysts on remazol golden yellow degradation under visible light irradiation

Photocatalysis is a promising solution for the degradation of dyes since this substance harms the environment. In addition, this process is environmentally friendly, especially while using low energy through visible light irradiation. In this study, Ni1-xVxFe2O4 nano-photocatalyst has been prepared using the sol-gel method. After freeze-drying and calcination processes, the sample was characterised using the techniques of x-ray diffraction (XRD), FTIR, UV–vis DR spectroscopy, TEM, and Particle Size Analyser (PSA). The XRD results indicated that a majority of the crystalline phase in this material prepared is NiFe2O4 spinel. Then, the grain size of this spinel is in the range of 20–32 nm. UV–vis DR spectroscopy analysis indicated that the bandgap energy of spinel Ni1-xVxFe2O4 (where x = 0.1–0.5) is 1.6, 1.8, and 2.0 eV, respectively. FTIR analysis explained that catalyst functions as the photocatalyst, and maintains the structure after the reaction. Furthermore, results of dye photodegradation indicated that Ni1-x V x Fe2O4 nanocatalysts are all active and able to degrade remazol golden yellow (RGY) by more than 30% conversion under the visible light irradiation. In two stages of experiments to degrade RGY, Ni0.5V0.5Fe2O4 nanocatalyst has the best activity with more than 65% conversion. However, based on the linearity correlation in determining the order reaction, it is clear that the rate is a pseudo-first-order reaction and the best rate constant for reaction below 80 min, k = 0.0029 min−1 for Ni0.7V0.3Fe2O4 photocatalyst.

Effect of V on the Precipitation Behavior of Ti-Mo Microalloyed High-Strength Steel.

In this work, the precipitates in Ti−Mo−V steel were systematically characterized by high-resolution transmission electron microscopy (HRTEM). The thermodynamics and kinetics of precipitates in Ti−Mo and Ti−Mo−V steels were theoretically analyzed, and the effect of vanadium on the precipitation behavior was clarified. The results showed that the precipitation volume fraction of the Ti−Mo−V steel was significantly higher than that of Ti−Mo steel. The randomly dispersed precipitation and interphase precipitation (Ti, Mo, V)C particles coexisted in the Ti−Mo−V steel. When the temperature was higher than 872 °C, the addition of vanadium could increase the driving force for (Ti, Mo, V)C precipitation in austenite, resulting in an increased nucleation rate and shortened incubation period, promoting the (Ti, Mo, V)C precipitation. When the temperature was lower than 872 °C, the driving force for (Ti, Mo, V)C precipitation in austenite was lower than that for (Ti, Mo)C precipitation, and the incubation period of (Ti, Mo, V)C precipitation was increased. Moreover, it was also found that the precipitated-time-temperature curve of (Ti, Mo, V)C precipitated in the ferrite region was “C” shaped, but that of (Ti, Mo)C was “ε” shaped, and the incubation period of (Ti, Mo, V)C was significantly shorter than that of (Ti, Mo)C.

Improvement of Microstructure and Properties of Q235 Steel by Iron-Based Laser Cladding Coating

Laser cladding is a repair and surface-strengthening technology for the protection of metal parts. It is an effective method for improving the properties of various metal substrates. The process involves melting and solidifying alloy powder on the surface of the substrate. The aim of the present study was to explore the effect of iron-based alloy laser cladding coating on Q235 substrate. Three types of specimens were obtained from Q235 base material using a 5 kW cross-flow CO2 laser beam. Sample 1 and sample 2 were obtained by the addition of rosin to the iron-based alloy powder. Sample 3 was obtained through the addition of rosin and vanadium to the iron-based alloy powder. A gas curtain was used to wrap the molten pool of samples 2 and 3. The surface hardness of the specimens was determined using a Rockwell hardness tester, and the tensile strength was evaluated using the universal mechanical testing machine. The microstructure of the cladding coating was explored using an Olympus optical microscope and SEM. The results showed that the average hardness of sample 2 and sample 3 was 6.42% and 19.84% higher than that of sample 1. The average tensile strength of samples 2 and 3 was 7.42% and 10.37% higher than that of sample 1. The grain of sample 3 was finer than that of sample 2, and that of sample 2 was finer than that of sample 1 under the same magnification. Rosin minimized oxidation of the substrate, whereas the gas curtain prevented the entry of air into the molten pool, hence the improved properties of samples 2 and 3 compared with that of sample 1. Rosin and the gas curtain protected the powder from oxidation loss and improved the quality of the cladding coating. The results of the present study show that rosin reduced the oxidation of iron-based powder, whereas vanadium improved the hardness and strength of the substrate as well as refined the grain size.

Effect of vanadium addition on the corrosion behavior of S30432 austenitic heat-resistant steel aged at 650 °C for different times

Effect of vanadium addition on the corrosion behavior of S30432 austenitic heat-resistant steel aged at 650 °C for different times

High-Dispersed V2O5-CuOX Nanoparticles on h-BN in NH3-SCR and NH3-SCO Performance.

Typically, to meet emission regulations, the selective catalytic reduction of NOX with NH3 (NH3-SCR) technology cause NH3 emissions owing to high NH3/NOX ratios to meet emission regulations. In this study, V-Cu/BN-Ti was used to remove residual NOX and NH3. Catalysts were evaluated for selective catalytic oxidation of NH3 (NH3-SCO) in the NH3-SCR reaction at 200–300 °C. The addition of vanadium and copper increased the number of Brønsted and Lewis acid sites available for the reaction by increasing the ratio of V5+ and forming Cu+ species, respectively. Furthermore, h-BN was dispersed in the catalyst to improve the content of vanadium and copper species on the surface. NH3 and NOX conversion were 98% and 91% at 260 °C, respectively. Consequently, slipped NH3 (NH3-Slip) emitted only 2% of the injected ammonia. Under SO2 conditions, based on the NH3 oxidation reaction, catalytic deactivation was improved by addition of h-BN. This study suggests that h-BN is a potential catalyst that can help remove residual NOX and meet NH3 emission regulations when placed at the bottom of the SCR catalyst layer in coal-fired power plants.

Correction to: Effect of an Addition of Vanadium on the Mechanical Properties of the A6061 Alloy Deformed by Accumulative Roll Bonding

Correction to: Effect of an Addition of Vanadium on the Mechanical Properties of the A6061 Alloy Deformed by Accumulative Roll Bonding

Artificial Neural Network Modelling of the Effect of Vanadium Addition on the Tensile Properties and Microstructure of High-Strength Tempcore Rebars.

In high-strength rebar, the various microstructures obtained by the Tempcore process and the addition of V have a complex effect on the strength improvement of rebar. This study investigated the mechanism of strengthening of high-strength Tempcore rebars upon the addition of vanadium through artificial neural network (ANN) modelling. Various V contents (0.005, 0.072 and 0.14 wt.%) were investigated, and a large amount of bainite and V(C, N) were precipitated in the core of the Tempcore rebar in the high-V specimens. In addition, as the V content increased, the number of these fine precipitates (10–30 nm) increased. The precipitation strengthening proposed by the Ashby–Orowan model is a major contributing factor to the yield-strength increase (35 MPa) of the Tempcore rebar containing 0.140 wt.% V. The ANN model was developed to predict the yield and tensile strengths of Tempcore rebar after the addition of various amounts of V and self-tempering at various temperatures, and it showed high reproducibility compared to the experimental values (R-square was 93% and the average relative error was 2.6%). ANN modelling revealed that the yield strength of the Tempcore rebar increased more significantly with increasing V content (0.01–0.2 wt.%.) at relatively high self-tempering temperatures (≥530 °C). These results provide guidelines for selecting the optimal V content and process conditions for manufacturing high-strength Tempcore rebars.

The influence of boron on the resistance to abrasion of quenched low-alloy steels

The paper attempts to determine the influence of boron in the presence of chromium, vanadium and titanium on abrasion resistance and wear mechanisms using low-alloy steels as an example. The obtained tribological properties were correlated with the hardness, carbon content and prior austenite grain size. Tribological tests – the dry sand-rubber wheel test – were conducted in the presence of loose abradant, and the major wear mechanisms were then determined using scanning electron microscopy. The results indicate that the improvement of resistance to abrasion may be supported by the combined addition of chromium, boron and vanadium. For unalloyed or chromium steels, a micro-addition of boron provides no benefits in terms of improving tribological properties.

Application of CeO2-V2O5 catalysts in the oxidative desulfurization of 4,6-dimethyl dibenzothiophene as a model reaction to remove sulfur from fuels

Oxidative desulfurization (ODS) is an excellent alternative for removing sulfur from fuels and the accurate choice of catalyst is essential in obtaining good conversion. In this study, V2O5 and CeO2 catalysts and their mixture were prepared by incipient impregnation method from ammonium metavanadate and cerium chloride as precursors. The catalysts were characterized by different physicochemical techniques. The acidity of the catalyst was measured potentiometrically by titration with pyridine and using a platinum electrode. The catalytic properties of the synthesized catalysts were evaluated in the ODS of 4,6-dimethyl dibenzothiophene. Acidity increased with the addition of vanadium, which generated more variants in the oxidation state of V2O5 and improved the catalytic activity. The vanadium catalyst with the highest amount of vanadium oxide achieved a conversion rate of nearly 100%, renders a viable catalyst for sulfur removal. Factors such as acidity and surface area affect the catalytic activity.

Structure formation of abrasive-resistant coatings

The paper presents the results of the study of abrasion-resistant coatings obtained by surfacing on alloying compositions Fe-Cr-Mo-V-C and Fe-Cr-B4C-Mo-C.It is established that with the increase of chromium in alloying compositions from 2% to 10%, the hardness and wear resistance of coatings increases due to the formation of a significant amount of complex alloyed carbides.The microhardness of the structural components of the deposited coatings correlates with the percentage of carbido-forming elements. Chromium-based coatings with the addition of vanadium, molybdenum and boron have shown high wear resistance under abrasive wear

Outstanding high-temperature strength of novel Fe–Cr–Ni–Al–V ferritic alloys with hierarchical B2–NiAl precipitates

We designed and developed a novel ferritic alloy, which reveals excellent high-temperature yield strength enhanced by coherent hierarchical precipitates. The composition of designed ferritic alloy was tailored via addition of Vanadium into a Fe–Cr–Ni–Al alloy to control the size and volume fractions of coherent B2–NiAl precipitates. The evolutions of microstructures, mechanical properties, and strengthening mechanisms at 973 K were examined by the experimental efforts coupled with theoretical approach, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, compressive mechanical tests at 973 K, and theoretical (strengthening calculations) approach. It was found that the vanadium results in the reduction of the lattice misfit between B2–NiAl precipitate and matrix and decrease of the precipitate size. Furthermore, a hierarchical structure in the precipitate, i.e., nano-scale Fe23Zr6 phase within the B2–NiAl precipitate, was established in V-containing ferritic alloys, which plays a vital role in enhancing the yield strength at 973 K.

Characterization of a novel maraging steel for laser-based powder bed fusion: optimization of process parameters and post heat treatments

A novel maraging steel with vanadium supplement called Specialis® has been developed for additive manufacturing by powder bed fusion using a laser beam. This study characterized this material after processing and post-processing. An intensive process optimization was carried out by means of a single track melt pool analysis to investigate optimal parameter sets for manufacturing of dense parts. Furthermore, the development of post heat treatment strategies and their influence on mechanical and microstructural characteristics of the material was evaluated. Two main concepts of direct aging treatment (AT) and solution treatment followed by aging treatment (ST+AT) were tested by dilatometry, to analyse the material behaviour with different initial microstructures: as-built and recrystallized. Both heat treatments resulted in a considerable improvement of hardness after only 2 h of aging, increasing to approximately 700 HV and 760 HV respectively, which exceeded the peak hardness of commonly known maraging steel 18Ni300 (660 HV after 6 h). These results were confirmed by tensile tests, where a tensile strength of more than 2300 MPa was achieved. Alongside the precipitation hardening known for maraging steels, the increased hardness was a result of grain refinement due to the addition of vanadium.

Effect of V addition on tribocorrosion wear behavior of boride layer produced on AISI 1040

In this study, the effect of the addition of vanadium (V) on the densification, microstructure, and wear behavior of borosintered powder metallurgy steels was investigated. Ball-milled powders containing 0, 1, 5 and 10 wt.% V were cold-compacted under 200 MPa pressure and then subjected to borosintering at 1100°C for 2 h in ambient air. The characterization of the boride layers formed after borosintering was conducted by scanning electron microscopy, X-ray diffraction, microhardness tests, nanoindentation, surface roughness measurements, and ball-on-disk-type wear tests. Wear testing was carried out under 10 N load for a total sliding distance of 250 m in ambient air and in a 3.5% sodium chloride (NaCl) solution. While the thickness of the boride layer decreased with increasing V content, its hardness and modulus of elasticity also increased, owing to the formation of additional vanadium boride (VB) and vanadium carbide (V2C) phases. Wear resistance increased with increasing V content, and the samples tested in 3.5% NaCl displayed lower coefficients of friction and higher wear resistance compared to the samples tested in ambient air. Reduced wear in 3.5% NaCl was attributed to the cooling and lubricant effects provided by the 3.5% NaCl solution.

Contribution of vanadium particles to thermal movement of correlated two-dimensional pancake Abrikosov vortices in Bi-2223 superconducting system

This article breaks new ground in understanding of variation in the magnetic strength performance, flux pinning and energy dissipation mechanism of polycrystalline bulk Bi1.8Sr2.0Ca2.2Cu3.0Oy (Bi-2223) superconducting materials added with the different vanadium concentration level (0.0≤x≤0.30) under the magnetic field strengths applied up to 5T for the first time. We provide the sophisticated and phenomenological discussions on the magnetoresistivity measurement results in three main sections along the paper. All the findings show that the increase of both the vanadium concentration in the crystal structure and external magnetic field strength damages significantly the magnetic strength performance, vortex dynamics, flux pinning ability and vortex lattice elasticity of bulk Bi-2223 superconducting ceramics. The vanadium addition promotes thermally the movement of correlated two-dimensional (2D) pancake Abrikosov vortices between the in-plane Cu–O2 layers in the valance band, vortex lattice elasticity, vortex dynamics, distance for interlayer Josephson couplings and flux pinning centers and the theoretical computations confirm the remarkable degradation in the formation of super-electrons in the Bi-2223 crystal system. Thus, the vanadium addition is anticipated to be one of the best selectable materials to examine the differentiation in the thermal movement of correlated 2D Pancake Abrikosov vortices in the bulk Bi-2223 superconducting system.

Effect of Vanadium and Rare Earth on the Structure, Phase Transformation Kinetics and Mechanical Properties of Carbide-Free Bainitic Steel Containing Silicon

Carbide-free bainitic (CFB) steels with a matrix of bainitic ferrite and thin layers of retained austenite, to reduce the manufacturing costs, usually do not contain alloying elements. However, a few reports were presented regarding the effect of alloying elements on the properties of these steels. Thus, this study evaluates the effects of vanadium and rare earth (Ce-La) microalloying elements on the structure, phase transformation kinetics, and mechanical properties of carbide-free bainite steel containing silicon fabricated by the casting and austempering procedure. Optical and scanning electron microscopy (OM and SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) were used to study the microstructure and phase structure. The transformation kinetics were examined by a dilatometry test. Hardness, tensile, and impact tests evaluated the mechanical properties. Due to adding alloying elements, the fracture toughness and change in matrix phases relation was studied by the crack tip opening displacement (CTOD) test and SEM fractography. The microstructure of the silicon added sample was completely carbide-free bainite. The test results showed vanadium helped CFB formation, even in continuous cooling. The primary austenite grain (PAG) size grew by vanadium addition. The EBSD phase map illustrates an increment in the percentage of retained austenite by vanadium. In contrast, the addition of 0.03 wt% rare earth reduced the primary austenite grain size and reduced the retained austenite content. The results of the dilatometry test confirmed that vanadium and rare earth addition both reduced the critical cooling rate of the bainite transformation. Vanadium leads to an earlier cessation of bainite transformation, while rare earth elements postpone this transformation. Mechanical tests showed that the tensile strength of carbide-free bainite steels was strongly influenced by the morphology and volume fraction of austenite. Retained austenite, when transformed to martensite during the transformation-induced plasticity (TRIP) phenomenon, leads to increased tensile strength and fracture toughness, or retained austenite with a film-like shape prevents the growth of cracks by blinding the crack tip. The result of the CTOD test exhibited that retained austenite plays the leading role in increasing crack resistance when TRIP occurs.

Structural and stability of B2 FeCo1-XVX and Fe1-XCoVX systems: Cluster expansion approach

Fe-Co alloys are considered good candidates for high-temperature applications due to their high saturation magnetisation and Curie temperature. However, these alloys show low levels of ductility at room temperature. In this study, cluster expansion was employed to probe the thermodynamic stability of the FeCo1-XVX and Fe1-XCoVX alloys. Ten new stable structures were found from both FeCo1-XVX and Fe1-XCoVX systems. Their stability was observed by deducing the heats of formation, and it was found that VFeCo2 and VFe2Co (P4/mmm) are the most thermodynamically stable phases. The results also showed that vanadium prefers the Co-site rather than the Fe-site substitution. The calculated Pugh’s ratio and Poisson’s ratio confirm that alloying with V effectively improved the ductility. It was also found that VFeCo2, VFe2Co, VFe4Co3 and FeCo showed a positive shear modulus condition of stability for the structures. The ternary addition of V in the FeCo system resulted in enhanced magnetic properties. Thus, ternary systems with vanadium addition enhance the ductility of the Fe-Co systems, and these alloys could be used to develop future magnets.

High doses of catecholamines activate glucose transport in human adipocytes independently from adrenoceptor stimulation or vanadium addition.

BACKGROUNDWhen combined with vanadium salts, catecholamines strongly activate glucose uptake in rat and mouse adipocytes.AIMTo test whether catecholamines activate glucose transport in human adipocytes.METHODSThe uptake of 2-deoxyglucose (2-DG) was measured in adipocytes isolated from pieces of abdominal subcutaneous tissue removed from women undergoing reconstructive surgery. Pharmacological approaches with amine oxidase inhibitors, adrenoreceptor agonists and antioxidants were performed to unravel the mechanisms of action of noradrenaline or adrenaline (also named epinephrine).RESULTSIn human adipocytes, 45-min incubation with 100 µmol/L adrenaline or noradrenaline activated 2-DG uptake up to more than one-third of the maximal response to insulin. This stimulation was not reproduced with millimolar doses of dopamine or serotonin and was not enhanced by addition of vanadate to the incubation medium. Among various natural amines and adrenergic agonists tested, no other molecule was more efficient than adrenaline and noradrenaline in stimulating 2-DG uptake. The effect of the catecholamines was not impaired by pargyline and semicarbazide, contrarily to that of benzylamine or methylamine, which are recognized substrates of semicarbazide-sensitive amine oxidase. Hydrogen peroxide at 1 mmol/L activated hexose uptake but not pyrocatechol or benzoquinone, and only the former was potentiated by vanadate. Catalase and the phosphoinositide 3-kinase inhibitor wortmannin inhibited adrenaline-induced activation of 2-DG uptake. CONCLUSIONHigh doses of catecholamines exert insulin-like actions on glucose transport in human adipocytes. At submillimolar doses, vanadium did not enhance this catecholamine activation of glucose transport. Consequently, this dismantles our previous suggestion to combine the metal ion with catecholamines to improve the benefit/risk ratio of vanadium-based antidiabetic approaches.

Improving mechanical properties in high-carbon pearlitic steels by replacing partial V with Nb

The effects of combined addition of niobium (Nb) and vanadium (V) on the transformation, microstructure and mechanical properties of high-carbon pearlitic steels were investigated. In-situ observations on a high-temperature laser scanning confocal microscope (LSCM) were conducted to study the pearlitic transformation, the results from which indicate that single V or combined Nb and V addition led to higher transformation temperature and more pearlitic nucleation sites. But the growth rate of pearlite was significantly impeded due to the smaller diffusion coefficient of carbon, resulting in the refinement of the interlamellar spacing and nodule size of pearlite. In addition, compared to the base steel, single V addition in high carbon pearlitic steels was beneficial to the increase of strength, but it deteriorated the toughness, whereas the composited addition of Nb and V resulted in the increase of strength without the expense of the toughness. It is concluded that replacing part V with similar content of Nb is very promising since the impact toughness of the Nb + V steel is increased by 21% without the expense of the strength compared to the V-microalloyed steel. Nb and V strengthened pearlitic steels primarily due to the precipitation of M(C,N), thinner pearlite interlamellar spacing and smaller pearlite nodule size. Compared to the V steel, the improvement of toughness in Nb + V steel was mainly attributed to the smaller nodule size and more uniform grain size distribution. In summary, under the premise of similar microalloying element amount in high-carbon (∼0.77 wt%) pearlitic steels, replacing part V with Nb is beneficial to obtain the finest microstructure and the best comprehensive mechanical properties.